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Do helicopters need to use yaw pedals to fly a coordinated turn?
I recall years ago, when I took a helicopter tour, I noted the pilot simply moved the cyclic left or right to bank the helicopter and initiate a turn. No pedal input was made whatsoever, and the ride seems completely fine.
In many fixed wing aircrafts, if rudder is not applied during the entry of a turn, the airplane will have a tendency to yaw to the opposite direction due to the drag induced by the ailerons.
Is pedal (rudder pedal? what are they called in a helicopter?) input necessary for turns in a helicopter?

"rudder pedal? what are they called in a helicopter?" They are called "anti-torque pedals" :)

In all types I have flown, you do subconsciously lead with a bit of  "into turn" pedal but someone watching the pedals, or even "following through" with their feet on the pedals, wouldn't notice.  In a similar fashion to fixed wing, you only add pedal to keep the string centred to continue to fly in trim.

As @Simon said, said, unless the pilot kept his or her feet on the floor, you might not be able to tell whether or not her or she made control inputs.

@RonBeyer FWIW, when I flew helicopters "rudder pedals" was the common term used to refer to them, and often just "pedals" (make a pedal turn to the right ... ) though strictly speaking you are correct.  Might depend on where you are flying, and with whom.

Many helicopters have different flight characteristics, but for general information you can always look in the FAA Helicopter Flying Handbook, this is from Chapter 9:
This is from a section on the four fundamentals of flight (straight-and-level, turns, climbs, and descents):

Anticipate the following characteristics during
  aggressive maneuvering flight, and adjust or lead with
  collective as necessary to maintain trim and torque:

Left turns, torque increases (more antitorque).
  This applies to most helicopters, but not all.
Right turns, torque decreases (less antitorque).
  This applies to most helicopters, but not all.

So some (most) helicopters do require some torque pedal movement for aggressive maneuvering, but the pilot may have anticipated this and added the correction prior to beginning the turn. You may not have noticed as much pedal movement as you would in a coordinated turn for an airplane, or the helicopter you were riding in had different flight characteristics and was not maneuvering aggressively enough to need it.
Many helicopters "wind vane" pretty well, that is that they stay aligned with the relative wind at high speed. It could be that the helicopter you were in was travelling at a high enough rate of speed that a large (or any) correction was not needed to maintain proper alignment.
For an example of how speed cancels out the need for anti-torque control, see this article about a helicopter pilot that lost the tail rotor and continued to fly for half an hour to a proper landing site.

Coordinated flight means that the airflow over the fuselage flows along the longitudinal axis of the aircraft.
The main risk of uncoordinated flight in an airplane is the possibility of entering a spin.
But helicopters don't spin, and uncoordinated flight is not dangerous in them in the same way as in fixed-wings. This means that helis can fly at any angle to the direction of flight, which is one of the main benefits of flying them.
That being said, helis are equipped with a flight instrument invented by the Wright Brothers -- the yaw string.  They are taped to the bubble, and in forward flight the pilot keeps the yaw string aligned with the fuselage by using the pedals.
The main benefits of coordinated flight in a heli are fuel efficiency and passenger comfort.

To go into a spin you need both uncoordinated flight and a stall... This can happen at high speeds, but you would have to be doing some pretty aggressive maneuvers to enter an accelerated stall/spin.

Excellent answer but note to the OP that there are airspeed limits to out of trim flying.  Exceeding these can be dangerous.  Flying out of trim at high speed is a bad thing.

I stand by my statement. The risk of a spin is uncoordinated  flight. No uncoordinated flight means no spin. A stall can happen at any airspeed and any attitude.

Fixed wing aircraft that deflect their ailerons experience adverse yaw: the aileron deflecting downwards experiences more drag than the one deflecting upwards, and this creates a yawing moment in the wrong direction. The magnitude of the effect depends on variables like aspect ratio, wing span, airspeed etc. It is this yawing affect that would be compensated by pedal input.
Helicopters effectively tilt the lift vector to the side where they need to go to, there is no adverse yaw effect that requires compensation from the pedals.
Both fixed wing and rotary wing aircraft experience side slip when only stick and no pedals are applied in a turn - to a limited extent due to directional stability in forward flight. The vertical fin provides this stability, and in helicopters the tail rotor as well: increase in side slip angle causes a change in angle of attack at the tail rotor, which results in a stabilising thrust change. But self stabilisation needs a slip angle to create force. Like Simon says, a true coordinated turn always requires pedal input.

Unlike fixed wing aircraft, helicopters require constant rudder application as compensation for main rotor torque. So there will be adjustments to be made in a forward flight mode turn, but the torque differential from power changes, not sideslip from drag, will be the overriding factor.

Short version:
Yes, helicopters require anti-torque correction to achieve co-ordinated flight.
However, co-ordinated flight is usually not necessary/desirable

This answer could be improved by adding the long version.


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How does the FADEC prevent compressor stall during rapidly increasing thrust demand?
My understanding is that if the demanded thrust is increased rapidly on a jet engine (for example going from nearly idle to TOGA during a go-around), the engine will likely experience a compressor stall: the combustion chamber is demanding a high quantity of air, but the front of the engine is unable to spin up and cope with the demand in such a short period of time.
This is the reason why engines spools up slowly: the FADEC is carefully controlling the amount of fuel increase to prevent a flameout; pilots should anticipate this delayed response compared to a piston engine.
My question is how exactly does the FADEC do this? Which parameters (air temperature / pressure) are being monitored, and what are the signs which the FADEC can detect such that it knows it has reached the limit of fuel increase?
For example is it something like monitor air pressure at X while increasing throttle, if X exceeds a certain value, stop increasing throttle until X drops?

FYI, you can also have a related compressor operability issue when decreasing thrust demand quickly.  i.e. if you are at TO and suddenly chop throttle to idle, the FADEC does not decrease fuel flow immediately but pulls it out over a few seconds to allow the core to slow down gradually.  If it detect a rejected takeoff (i.e. still on the ground), it pulls fuel out a little more quickly.

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How can I cross verify my propeller thrust?
I'm simulating a propeller in Ansys and im getting a thrust of 2000N. The forward speed is 85m/s and 240.25 rad/s angular velocity and the diameter of the propeller is 1.8m. Since I'm not able to find any reference values yet I can't tell if my model is accurate. Does this sound like a reasonable value?

Does it seem reasonable to you? (If not, why not?) What makes you think it might not be reasonable?

500 lbs thrust at 170 knots @ 2300 rpm 1.8 meter prop is probably "in the ball park", especially if the prop pitch can be adjusted.  But please try to show at least some effort to find references.  We can help more with a specific question about calculations.

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How to calculate EGT Margin for P&W engines (PW1100g) ? (Theta parameter correction)
My goal is to obtain engine baselines and calculate EGT Margin for Pratt&Whitney PW1100g engines (specifically, PW1133GA-JM)
I have a large dataset of engine reports recorded during takeoff. I have applied the following standard formulas for parameter correction:

$\theta = (T2 + 273.16) / 288.16$
$\delta = P2 / 29.92$
$EGTK = (EGT + 273.16) / \theta ^ {0.84} $
$N1K = N1 / \sqrt{\theta} $
$N2K = N2 / \sqrt{\theta} $

Then, I plotted the corrected values against N1K as shown below.

Comparing my results to ones found in this paper I found that my EGTK points do not form a straight line therefore I think my correction formulas are wrong.
My questions are:

What adjustments should I make to my formulas?
How do I consider bleed flags in corrections?

I will appreciate any help and any information related to my problem.


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Help ID a biplane my Dad flew as a late 1920's barnstormer
My Father flew this ship. Can you help ID it. Photo was taken at the de Havilland Moth Factory
Can't figure out what the heck it is,

Looks like the tail of a DH-60
Consolidated PT-1 "N" struts (with strut connecting upper & lower flaps)
Engine appears to be a Hispano type V-8 (same exhaust on starboard side)
Upper wing to fuselage connection over passenger seat is really strange
Never have seen 3 row engine cooling vents like that on any DH model

Looks like a DH 60 variety. The G-CA registration is Canadian, so it is deHavilland Canada. The last two letters of the registration are not painted on yet. Do you have more information? Did you dad own the aircraft? Was it registered on his name or a company? Do happen to know the registration of the aircraft? Company name, family name?

The DHC facility on Trethewey Dr was built right around the time the registration CF was adopted so that's likely something from the mid 20s, maybe a one-off of some kind. It doesn't look "DeHavilland-y" at all to me. '

Little more information, I don't know for sure, but the rear of the lower wing to fuse isn't any DH-60 variant I'm familiar with. The landing gear isn't either, no axle cross strut. Owner (Mr. 'Han'?) I THINK had something to do with late 20's Blackwell Oklahoma's Globe Oil. Unknown registration. Dad, age 29, is S T Stanton.

This is a 1924 Martin 70 Commercial G-CAVE. It was an unsuccessful aircraft from the Glenn L. Martin Company, only two or three being built. G-CAVE started life as NC2545 (manufacturer serial no.96), one of only two airframes ever registered, and was exported to Canada on 10 June 1928.
Shortly after, your father S T Stanton piloted this aircraft with its new owner E V Hemple as passenger, in the National Air Races of 1928, from Windsor, Canada to Mines Field, Los Angeles (now LAX):

William H. E. Drury, youthful pilot of London, Ont., flying a Waco,
won the international race from Windsor, Canada in 19 hrs., 55 min.,
41 sec., averaging 107.63 miles per hour. The distance was 2,145 miles
with five controls. Drury won first prize of $5,000, ﹩750 lap prizes,
a Stetson hat, a watch and two pairs of chaparajos ... S. T. Stanton
and E. V. Hemple, flying a Martin bi-plane, were forced down by engine
trouble almost within sight of their destination, at Fontana, forty
miles from Los Angeles.
Popular Aviation November 1928

Aviation Week reports:

S. T. Stanton's Martin was forced down at Fontana, almost with
striking distance of the finish of the race by engine trouble an hour
or so after Drury had completed the course. Had he arrived by 5
o'clock that afternoon he would have won the third prize of $1,500. E.
V. Hemple, owner of the plane, was with Stanton as a passenger.

Here it the plane before export -

Martin 70 Commercial, with extended exhaust pipe. This is the same aircraft as in your photo. source

Martin 70 newly manufactured in 1924. The photo shows the luggage / passenger area (forward of the pilot's cockpit) faired over.

Martin 70 Commercial, unknown date
The 70's antecedent was the Martin 66 "Night Mail", which was even less successful - only one was built. As well as the 70, the subsequent Martin N2M-1 (another design that didn't go into production) was also derived from the 66, all sharing the distinctive ogee front-end sweep of the vertical stabilizer.
It is reported "several" 70s were built, but only two airframes were ever registered. There is a little bit more about the aircraft here, but it is a bit confused, starting out with your aircraft (96) before jumping to the other airframe (94 / NC2544). I've included a page from Flight Magazine.

G-CAVE is the only G-CA registration that matches your aircraft.

Original photo, showing the addition of an extra exhaust pipe to vent behind the pilot.

Amazing detail you uncovered. Thank you very much


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Can the emergency slide be re-used after it has been deployed?
Can the emergency slides be re-used and re-packed after they have been deployed, assuming no damage is done?
For example, I heard of a case where the slide was accidentally deployed due to opening of the main door when it was "armed". This resulted in the slide partially deploying and landing on the air bridge.

Sure. In fact, the emergency slides have to be removed from aircraft and tested periodically under present regulations.
According to Lufthansa Technik:

Under current regulations each emergency escape slide must be removed from the aircraft every three years and checked in the workshop.
The slide is tested by "flat firing" the slide on the floor; the test confirms that the slide inflates properly within two to ten seconds, depending upon the aircraft and type of slide.
The inflated slide is also checked in the workshop at over-pressure to test that seams retain their integrity under extreme loads. The slide is also tested for its ability to remain properly inflated for several hours.

This testing cycle varies according to the OEM/operator. For example, according to Boeing, the B747-400 slides have a 12 year testing cycle. In addition, they are checked regularly depending on various factors like its age etc. According to Udo Janssen, Lufthansa Technik’s director of emergency equipment,

At approximately 15 years of age, the first signs of aging appear with the materials—porosity of the fabric, seam peal, or pack board delamination. That is the reason why, after 15 years, the OEMs change the inspection schedules from three-year intervals to yearly cycles.

During these tests, the slides are usually inflated either fully or partially. So, the undamaged slides can certainly be reused.

The deployment system doesn't use explosives like airbags do? I can imagine redeployment gets a little trickier with those.

@ They use gas cannisters

Ah, that explains a lot :-)

@Mast Packing enough explosives to inflate a large slide into the door of a pressurized airplane does not seem like a good idea for improving safety. :) Also, airbags are meant to inflate as close to instantaneously as possible and then almost immediately deflate. Those (especially the latter) are not desirable properties for an emergency evacuation slide.


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How to slow down a seaplane on water?
A seaplane cannot use brakes to slow down, like a land-based aircraft. So how does one slow it down?
I am asking this in the context of landing, taxiing, aborted takeoff etc., as long as the plane is on the surface of water.
I imagine a few possibilities:

Land on a really long "strip" to ensure that water friction slows the aircraft down enough, then remember to not taxi too fast because you cannot slow down
If the plane has a variable pitch propeller, probably you can go to beta range to produce reverse thrust (what to do if the plane has a fixed pitch propeller?)
Steer left and right repeatedly (but wouldn't this cause stress on the airframe / chance to flip the plane?)

The very fact that the seaplane is on water does an astoundingly good job of slowing it down. Sometimes too good. (yes, okay, that one was pilot error)

If slowing down quickly is a necessity, wouldn't it be a simple matter to design in "water brakes", along the same lines as air brakes?

Related, if not a duplicate: How do seaplanes do run-up checks without brakes?

By the way, I only know of one constant speed propeller seaplane that can go into beta (that isn't a turbo-prop), an Aviat Husky, and I think its something like a $20,000 option.

Water is about 8 times more viscous than air. Granted, there is less aircraft in contact with the water on landing than there is with air when flying, but it does a great job of acting as a brake. To see this in action, head out to a popular water skiing lake during the summer and watch how quickly ski boats stop when the skier falls - boats don't have brakes. Boats can reverse direction on the prop, but there's no need to except when backing away from the dock.

@FreeMan viscosity is neglectable at the relevant Reynolds numbers; it's the higher density that makes water a so much better brake. And the density is not merely 8 times higher...

Water is more like 50 times as viscous (and 1000 times as dense) as air.

@FreeMan Actually reverse thrust in boats is routinely used to slow in a shorter distance when approaching a dock. Also anchoring, pivot turns, backing into a slip, etc. And multi-engine boats can use opposing thrust for even tighter maneuvering.

As already mentioned, decelerating from flying speed to a slow taxi speed occurs naturally at a much higher rate than when touching wheels down on a runway.  But there are tricks to minimize forward motion with the engine running when that matters (e.g. approaching a dock).  One method is to switch off one magneto, which decreases RPM and thus thrust (if you use this make it a habit to verify both mags are on right before EVERY takeoff).  Another is to head into the wind as much as possible and for maximum effect open one or both doors fully.

Unless you're planning on trucking a seaplane out of where you have landed it, you usually don't need to worry about slowing down on landing since you can land in a far shorter distance than you can take off. In other words, the landing water run is far shorter than the takeoff water run.
If you do want to shorten the water run or reduce your taxi speed, holding up elevator will do that. A few seconds after touching the water and at idle power, you can use full up elevator without fear of the aircraft lifting off again, and it will add the drag of the elevator plus change the attitude of the floats or hull to a high-drag, plowing attitude. I used to do that if where I wanted to dock was aft of the touchdown point and I wanted to quickly slow to a safe turning speed.
Most constant speed props (variable pitch) on reciprocating engines don't have a reversible pitch or beta, but that can be purchased as a modification on some. The major use of such is as an aid in docking, and for that it's really useful.
Steering left and right repeatedly doesn't impress me as a very good idea, but I suppose it would help a little, but very little since it wouldn't be advisable to do it until you're well off the step.
Deploying the water rudder adds a little additional drag. Depending on the wind conditions, putting in a little rudder to match cross-controlled ailerons also adds drag, but that's not generally used to slow down as I remember. It is used, though, when sailing the aircraft, for which it's standard procedure.
See also Chapter 4 of the FAA Seaplane Handbook.

Your first flight in a seaplane will impress you as to how much drag is offered by the floats / hull during water operations.
In general, seaplane pilots have three modalities of water operations.

Idling position. In this position, the floats / hull have a similar displacement as when the plane is at rest in the water. Low power is used, as on many planes it is possible kick up water which substantially erodes propellers.
Ploughing position. The aircraft is nose high, and the floats have less displacement than at rest, causing less drag. Generally ploughing is utilized when on rough water, as it helps keep the propeller out of water spray, reducing erosion and probability of damage.
Planing or on the step. The aircraft is nose high, and the speed is greater, permitting take off. Water rudders are retracted, and as float/hull displacement becomes less, the drag from water displacement and surface tension becomes less.

When landing, water displacement causes substantial drag and there is no need for brakes as might be needed on a land plane with a hard surface runway.
Beta is available on some seaplanes, but they are normally larger planes, which sit higher, and most frequently have turbine engines.  Even in a Cessna Caravan with floats, use of beta on the water is discouraged as it can increase prop erosion.  Again, it is not necessary for slowing the plane in normal operations.

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text:
Has there been an aircraft with multiple type of engines?
Has there ever been an aircraft that can fly using at least two different type of engines? For example, a piston engine and a turbine engine, or a piston engine and a electric motor.
To clarify the question:

It is not necessary to operate both engines at the same time. However the pilot must have the ability to switch from one engine to another engine while in the air.
The engines must generate power using completely different mechanisms.
VTOL/STOL aircraft (e.g. V-22, F-35) does not quality because the aircraft is simply directing thrust from the same engine elsewhere.
The question is not asking about variants of an aircraft model where each variant is fitted with a different kind of engine. Both engines has to be fitted on the same airframe and operable at the same time.

The answer that Peter linked includes the aircraft that immediately came to mind, the Rutan Voyager.  Different engine in the front than in the back.  Both used for takeoff, then one shut down for cruise.

You might want to clarify about whether aircraft whose purpose is to test new engine designs and have old engines as a backup are included.

@PeterSchilling That's exactly what the comment by Peter Kämpf said … :-)

@Ralph J: But (AFAIK, anyway) the Voyager's two engines were both of the same kind - standard 4-cylinder Continental aircraft engines.

Engines: Teledyne Continental, Front Engine: Type O-240, 130 hp, Rear Engine: Type IOL-200, 110 hp

@Ralph J: Yes, they're both the same type of engine: horizontally-opposed, 4-cylinder gasoline-burning internal combustion engines.  Increasing the displacement a bit does not make one a different type of engine, Now if one was a jet, a gas turbine, or even a diesel, then they'd be different types.

The B-36 Peacemaker quickly comes to mind, using 4 turbojet engines to augments it’s six diesel radial engines.
A number of proposed aircraft made use of multiple, different types of power plants.  The X-30 National Aerospace Plane, a reusable runway to orbit vehicle, used turbojet, scramjet and rocket engines at various stages of its proposed flight into space.  The new SR-72 hypersonic reconnaissance airplane is rumored to use a proprietary turbojet and scramjet powerplant built by Rocketdyne.  an experimental French fighter called the Nord 1500 Griffon, making use of a hybrid turbojet and ramjet for high speed flight.  Even business aircraft attempted with hybrid propulsion.  The ill fated Gulfstream American Hustler, used a PT-6 turboprop engine at low altitudes and a jet engine at high altitudes in an attempt to conserve fuel.
During the postwar era, hybrid turboprops and jets did make a debut, particularly as a solution for the problems early jet aircraft had recovering aboard aircraft carriers.  The Ryan Aircraft FR-1 Fireball was a hybrid powered fighter, looking much like a conventional WWII era piston powered fighter but had an additional jet engine in the tail of the aircraft to be used in high speed flight.
Some types of aircraft have used multiple types of jet engines.  This has been a popular solution for VTOL capable fixed wing aircraft.  The Yakolev Yak-38 Forger made use of a single R-28 engine for forward flight and combined that with a pair of RD-38 lift engines for VTOL operations.  Another impressive design was the Dornier DO 31 prototype V/STOL cargo aircraft which made use of a pair of Rolls Royce Pegasus turbofan engines combined with no less than eight Rolls Royce RB162-4D turbojets mounted in the twin wingtip pods for control during hover.

The Convair B-36 Peacemaker had six Pratt and Whitney radial piston engine propellers and four GE turbojets. The turbojets were used during takeoff and shut down during flight.

 image source Wikimedia Commons

The turbojets were also meant to increase speed while flying in hostile airspace.

Wikipedia lists 27 "mixed-power aircraft". Most were prototypes or were never even built, the only ones I can see that made it to double digits in their production runs were:

MiG I-250 (piston/motorjet, 12 built)
Martin P4M Mercator (piston/turbojet, 21 built)
Ryan FR Fireball (piston/turbojet, 71 built)
SNCASO Trident (rocket/turbjet, 12 built)

It looks like only two prototype Destroyers were built with the mixed propulsion.

@Todd Good catch, thanks! I didn't read the full details; updated.

That list is incomplete: there's also https://en.wikipedia.org/wiki/Category:Aircraft_with_auxiliary_jet_engines, which lists the Convair B-36, some variants of the Avro Shackleton, a civilian modification of the Fairchild C-119, the Fairchild C-123, the Lockheed P-2, the North American A-2, the Martin P4M, and a whole bunch of prototypes.

@Mark: Don't forget the Boeing KB-50 (112 converted from various versions of B-50) and KC-97L (81 modified from earlier KC-97Gs) tankers, both of which were equipped with dual turbojet pods to allow them to refuel fighter jets without the latter falling below their stall speed.

I would say that any aircraft equipped with JATO capabilities fits into your description. The only point it may not subscribe to is the first one, the pilot can not really switch between power sources although they can ignite the JATO rockets on command.
The space shuttle (if you want to include that as an aircraft) was powered by both liquid fuel rockets and solid fuel rockets.

The Screaming Sasquatch is a 1929 Taperwing (bi-plane) with a P&W 985 Radial Engine that they strapped a GE J85 with 3,000lb-thrust to the bottom of:

Source: EAA Vintage.org

The engines must generate power using completely different mechanisms.

If you allow your two engines to be to be built stacked one after the other, then fast jets such as Lockheed SR-71 Blackbird switch between the turbojet and afterburner as speed increases. Either could be considered an engine in their own right - a turbojet and a ramjet.

I think that "ramjet" would be a better word for both "afterburner" and "air breathing rocket".

@Agent_L The SR71's J58 engine is often called a "turboramjet" for that reason. Regardless of what you call it, though, it is very clearly designed and operated as a single engine, not as two separate engines.

@StephenS I think you've meant to direct your comment to the author of this answer, not to me.


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Anyone come across a concept of vertical spoilers on wings not perpendicular to the flow? As in not following the LE/TE sweep direction?
For reference, I am currently investigating vertically actuated spoilers for gust load alleviation for my master's thesis, and I was wondering, if the concept of non perpendicularly oriented spoilers to the flow direction have ever been tested computationally?
My current thesis plan is to modify a CRM (Common Research Model - A generic transonic transport aircraft model) geometry to include vertically actuated spoilers and simulate them on a FSI (Fluid-Structure-Interaction) framework for various gust loads, however, I was asked by my supervisor to maybe try to come up with a slightly novel idea or an improvement to an existing system, hence this idea came up.
My idea behind it was, If I could orient them in certain angles (basically fixed to the wing at certain angles, not make its angular orientation also a adjustable parameter), I can have a lot more freedom in terms of local loading over the wing, positions and amplitudes of the peak loads generated etc. This would open a lot of control options, which could deal with gust loads, possibly.
Practically I know it may not be very feasible, but I was interested in the idea of doing a FSI Sim to maybe design an optimal layout of a couple spoilers and/or show its effectiveness
I know it would be an extremely complex case, with a lot of variables. I thought of getting the ball rolling with a few simple cases, and varying only a few variables such as angle wrt the flow, height of spoiler deployment, at a fixed position over the wing.
Anyone has come across such use of spoilers? If so, could you direct me to a few references or papers that have studied them?
In the image, Blue lines indicate typical locations for spoiler hinges, The black angled lines is what I want to test

For simplicity reasons and time constraints, I will be ignoring the presence of flaps and control surfaces

Given that on a swept wing the boundary layer moves also outward, setting the spoiler inclined as the rightmost in your picture might actually be beneficial


text:
Nearly stalled on takeoff after just 3 hours training on a PPL. Is this normal?
I'm doing a PPL in the UK at an established flying school. The aircraft I'm training in is a Cessna 150.
Aside from a 1 hour introductory flying experience I have logged just 3 hours of flying with a qualified instructor.
The lessons I've had so far have covered basic flying controls, how to "book out" the aircraft, perform a walk around, and going through the pre-flight checklist.
During my last lesson I spoke to ATC for the first time to obtain clearance. My instructor told me what to say and allowed me to practice it first.
He then said he wanted me to perform the take off.
I was surprised and asked him to clarify this since I didn't think this would be normal after only 3 hours of training. After we had lined the aircraft up on the runway he instructed me to pull back on the yoke when the ASI reached a certain speed (I can't remember what the speed was but from memory around 70 kts). For reference I was in the left seat; instructor was in the right.
I waited for the ASI to reach the agreed speed and then pulled back. We left the ground but my instinct - bearing in mind I'd never done this before - was to pull back harder than I needed to. My instructor very quickly told me he had the controls. To which I repeated "you have control" as per the manual I've been given.
His reactions were extremely quick and he corrected whatever I had done.
I don't know exactly what happened and felt embarrassed about asking afterwards. I imagine I nearly stalled the plane on take off.
My instructor is a former commercial airline pilot for a major UK airline. As I mentioned the flight school is well established and well respected.
The remainder of my lesson went ok. I was learning about PAT (Power Attitude Trim) which he said I did reasonably well at.
I haven't had any lessons since and felt a bit uncomfortable from the experience, which was a couple of weeks ago.
My questions for the community are:

Is it "normal" to be asked to perform a take off after just 3 hours of training?
What did the instructor to do recover what I'd done with the yoke? I presume he levelled off - but I'm unsure whether that's right given we couldn't have been more than around 100 ft in the air when he took control.
What advice would you give me going forward about dealing with this? Should I speak to my instructor and explain it made me uncomfortable? Or should I go as far as finding a new instructor?

I did all my pilot training in the UK. Similarly I only had an hour or two of previous experience before starting my training. Speaking to fellow pilots, I would say that it is normal to be asked to perform a takeoff after just a few hours of training. In fact, I took off on my first flight and landed my second flight. This is very much dual controls flying, so the instructor would be “guarding” the controls - keeping their hands and feet close to them so they can react quickly if they need to. They should also thoroughly talk through the procedure before they ask you to fly it.

The instructor was probably pleased with your progress. He needs to "test' you a little bit. Of of the key aspects of instructing is you have to let someone try something and NOT intervene too quickly, because you have to see if your student recognizes and corrects without intervention. So there's often a go-no-go knife edge where you let your student get to the edge of trouble before you take over.  That being said, you should have been carefully briefed beforehand, and a clear demonstration done by the instructor before letting you try. Assuming that was done, what happened was no big deal.

It is normal for student pilots to be introduced to all phases of flight, and there's nothing inherently wrong with introducing you to take off after 3 hours of instruction - this is a dual control aircraft and I assure you the instructor was fully prepared to take control. I also pretty much guarantee you that he was fully expecting you to put in more input than was needed.
To "recover" all they would have done was lower the nose - remember what you learned later in the lesson about power & attitude. By lowering the nose, it would have increased the speed.
Absolutely you should speak to your instructor about this, and they probably should have talked through it in a debrief after the lesson. If they did anything "wrong" here, it is not briefing you on the ground about what was going to take place, and what to expect.
Don't worry too much about this though, you are 3 hours in and you have plenty of time and space to learn.

For what it's worth, I did much of my PPL(A) training in the UK and I just went back to check my logbook. Take off and climb to downwind is Exercise 12. The first time I did that was about 8 hours into training. Your instructor clearly had more confidence in you than mine had in me! In my recollection, I did take off with the instructor "following through" on the controls before that - but the official introduction of that exercise was on my 6th flight.

Interesting point about the exercises. I've been given the Pooley's Volume 1 ("Flying Training") book by the flight school. The PAT exercises I mentioned in my question are around exercise 4, and everything up to that point is consistent with the other things I'd learned so far. I'm not actually sure when take off is discussed but know it hasn't been covered prior to exercise 4, which is partly why I asked the question. Indeed I don't even know when it appears in the book for the simple reason I haven't got to that yet.

Same, I didn't attempt a takeoff until 8 - 10 hrs in

Proper training involves as much educational preparation before attempting a task as possible

you do not want to learn to fly aircraft by trial and error

Firstly, it's the instructors job to save the situation.  That's their job.
You should feel good about one thing:  yielding control quickly without argument.

$You$ $did$ $that$ $right!$.

Though it may comfort you to know that none other than test pilot Hanna Reitsch did this in early glider training$^1$, yanking the stick hard is an instinct that must be overcome in training.

pulling the stick too hard can cause the aircraft to stall

This is why your instructor most likely pushed the stick forward to lower angle of attack and to maintain airspeed.
Also, more rudder may have been applied to help hold the aircraft straight against engine/prop "p factors"$^2$.

it is normal to get "saved" in flight training several times

But it is up to you to explain to your instructor that this approach made you feel very uncomfortable, but don't hold back from asking questions about what happened.
One last word of advice:  since lift is proportional to the square of airspeed,  if you rotated at 70 knots and your 150 stalls at 50 knots there was no need to yank the stick at all.

review trimming for takeoff with your instructor

$^1$ from the autobiography Fliegen-mein Leben
$^2$ you will be learning about these in training too.

There's nothing wrong with being introduced to takeoffs early on. I do think your instructor could stand to have briefed you better on it. The goal isn't to pull the airplane off the ground- you want to rotate it into a specific pitch attitude and wait for itself to lift off on its own.

pull back on the yoke when the ASI reached a certain speed (I can't remember what the speed was but from memory around 70 kts)

This should very much be a memory item. Learn this by heart before your next lesson. I like to verbalize it during the takeoff roll (something like "tach green, temp green, pressure green, airspeed alive, rotate at 50"). In the 150s I'm familiar with the rotation speed is 50 knots or a little higher if your ASI is in mph. 70 knots would be weird to say the least.

I don't know exactly what happened and felt embarrassed about asking afterwards. I imagine I nearly stalled the plane on take off.

You should ask. There's nothing to be embarrassed about in primary flight training and you should never let embarrassment get in the way of learning or safety.
It could be that you were on the path to stalling (if you were actually close you'd have heard the stall horn blaring). It's also possible that you almost struck the tail on the ground. In either case, your instructor was prepared to keep anything bad from happening.


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How to get out of icing conditions asap?
We all know certain weather can cause ice to form on an aircraft, and the danger it poses. Obviously the best way is to avoid flying near these areas in the first place.
Let's say I happen to fly into one. Aircrafts have de-ice equipment such as de-icing boots, pitot heat, engine de-ice etc; but sitting there and flying through the ice-cold cloud does not seem to be a good idea. So something must be done to get the aircraft out of icing conditions asap.
What is the best course of action? Should I descend at normal speed? Or descend and pick up speed? Climb? Perform a 180? Would a weather radar (which reflects precipitations) help?

Chapter 8.2.2 Normal Procedures section of CAA Aircraft Icing Handbook (New Zealand) and AOPA Aircraft Icing

Depends on the aircraft.  In Schweizer 2-32, a terminal-velocity vertical dive with spoilers open might be wise.

well, you'd have to fly in whatever is the shortest route out of the icing conditions, obviously.
What that would be depends on your speed, wind, climb/descent performance, and how you entered icing conditions.
If you entered icing by climbing, diving may well get you out of it (but if you were climbing to avoid terrain...).
If you were turning left, turning right might do it (but were you turning left to avoid collisions?).
Etc. Etc.
IOW there's no universal answer, it's way too situational.

Aircrafts have de-ice equipment such as de-icing boots, pitot heat, engine de-ice etc;

Not all aircraft (in particular light GA ones) have equipment to deal with structural ice, and ones without it account for most icing-related crashes.
Carb ice does cause a crash now and then, but forgetting to apply carb heat is obvious pilot error. Pitot ice won’t directly cause a crash, but likewise, forgetting to apply pitot heat is obvious pilot error.

but sitting there and flying through the ice-cold cloud does not seem to be a good idea.

If you’re equipped for the rate of ice accumulation, then there’s no problem. Airliners knowingly fly into trace, light and even moderate icing conditions every day. They monitor the situation to make sure the ice is not building up faster than the plane can shed it, but in most cases, it’s a non-event.


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How is a meatball calibrated and checked?
The visual glide slope for aircraft landing on a carrier is a stabilized indicator, the "meatball":

Source.
The slope is about 4° relatively to the horizontal plane, and stabilized because the carrier is usually rolling, pitching, and heaving.
How is the meatball calibrated, and then checked for accuracy?

And here I was thinking this question was about in flight catering.

@IanF1: There is indeed some likeness.


text:
What precautions should be taken when flying near the magnetic poles?
Aerial navigation is designed to primarily use magnetic headings. Consider an international flight which flies a great circle route across the North Pole, or an aerial tour around the Atlantic area. What should the pilots do to avoid getting lost?
This question asks about VOR alignment, and this question discusses the coordinate system used; but neither discuss what the pilots should do in the cockpit. How do you align the HSI? And what happens if GPS has malfunctioned?

No international flights cross the poles.

@Simon Some flights fly close to the north magnetic pole though, though not the true pole.

@SMSvonderTann Can you provide an example?  The closest I can find is about 60 miles away.

See also “No aircraft crosses directly over the pole” - Why?

@Simon I'd say that 60 miles is "close enough", wouldn't you?

Is the question about the magnetic or the geographical poles?

You mention a GPS failure which is not a problem as there would be 2 or 3 IRUs still available. Do you have something else in mind?

@mins say it's a less sophisticated plane with no FMC, only traditional HSI & magnetic compass? Are these planes unqualified to operate in the area?

Possible duplicate of Is the heading used near the pole?

You raise an interesting question, and I assume you refer to flying near the poles using a lightly equipped general aviation aircraft. Airliners or jets usually have inertial navigation equipment that is working autonomously and will not be affected by pole proximity.
Several procedures could be taken in a general aviation aircraft to improve situational awareness:

You need indeed to deslave the HSI from the magnetic slaving transmitter in order to use it as a directional gyro manually slaved (see How does a horizontal situation indicator (HSI) work?). The directional gyro will have to be realigned manually regularly to compensate for precession (astronomical precession is 15°/hour at the pole, to the right at North pole, to the left at South pole).
Don't forget it is still possible to use astronomical navigation if you are in VFR conditions and able to see stars (at night) or the Sun (during day). This will not be very accurate but a precision better than 5 to 10 degrees could be reached without needing a sextant. Computing your location only from star positions is a complex operation, but it is rather easy to find out aircraft true heading thanks to the Sun or major stars relative position from aircraft nose. You could use this heading to manually realign your unslaved HSI/directional gyro.
Regarding GPS, it is strongly advised to check in advance GPS coverage near the pole using RAIM prediction function, either from the onboard GPS or using web servers. This will allow you to check the coverage should be assured according GPS satellite locations relative to your position (an outage is always possible). When flying in such remote locations I always bring with me a portable standalone GPS unit, in addition to panel mounted GPS.
Standard navigation (keeping track of position thanks to heading and clock) of course should be used and near coasts you could cross-check your computed position using landmarks, but above ice caps you will have few or no landmarks.
If you are lucky enough to have an inertial navigation platform on board, your position will be kept rather accurately independently of any other input, with an error of the order of 10 NM after 7 hours of flight.

The main issue you will encounter in a general aviation aircraft flying near the pole is their endurance is often limited, regulatory fuel reserves are higher than usual, airports are few and far apart, alternates may close quickly due to quickly changing weather conditions. This means that when you fly or are ferrying an aircraft in those regions, you could definitely not afford to get lost or not to be sure of your position.

What is the minimum equipment required to fly in a polar region and in an area of magnetic unreliability? From your answer it seems there is none. Is a VFR flight allowed?

What precautions should be taken when flying near the magnetic poles?

Near the top of the list would surely be to have lots of warm clothing and high-calorie food available in the event of a forced landing.


text:
Can a helicopter be "stalled" by pulling too hard?
In the PC game Arma 3, there is a helicopter-race game mode, in which the player tries to manipulate the helicopter to pass a serious of hoops as fast as possible in an AH-6.
In the game, if the player banks the helicopter then make a sudden and hard pull on the cyclic to make a turn while max collective is applied, the low rpm warning will sound, followed by a loss of power and a few seconds later loss of attitude control. The aircraft can be recovered by:

Lowering the collective
Releasing stick pressure
Leveling the aircraft

After which the rpm will increase back to normal again.
My guess explanation is as follows:

When max collective is applied, the blades are working hard by cutting air at a large angle of attack
When the aircraft is banked and aft cyclic is applied, the airflow relative to the aircraft is like when it is in a very high rate descend
The critical angle of attack is exceed on the rotor blades, they stall and cease to produce lift
Due to the greatly increased drag, the main rotor is unable to keep rpm up with its power, therefore rpm decreases
As rpm decreases, less lift is produced and the stall worsens.
By reducing collective, the drag of the blades is reduced, and rotor power is enough to keep rpm at normal range again.

Is my explanation correct? Can this happen in real life?

What you describe is completely unrealistic (but then again, I have never seen or heard of a PC simulator that accurately simulates helicopters in anything except the basic flight regimes).  Therefore, the answer to "can this happen in real life" is no.

@Simon perhaps you can add your own answer then?

The only answer I could give is no, it's not realistic.  If the question was "what would happen in real life if you used these control inputs" (with some more detail), that would be answerable.

About High Energy Maneuvers in a Helicopter: not quite like fixed wing flying

... if the player banks the helicopter then make a sudden and
  hard pull on the cyclic to make a turn while max collective is
  applied, the low rpm warning will sound, followed by a loss of
  power and a few seconds later loss of attitude control.

I don't understand what you mean by "loss of power" here (engines are red lined and don't produce any more power?) ... but to proceed

The aircraft can be recovered by:(recovery steps)

While the recovery steps are rational, the point is to not wait that few seconds if you droop Nr.  I am not sure if the simulation is trying to model retreating blade stall or not, but the response to droop in a max performance maneuver cannot be delayed.
With max collective and a maneuver that induces low NR you don't wait: you reduce the load on the rotor head.  You do that because the engines aren't able to keep the rotor turning based on the load you've put on the system.  If you keep the load on you just make the problem worse.  (In that regard, the simulation is more or less faithful to real life ...)

My guess explanation is as follows:

1. When max collective is applied, the blades are working hard by cutting air at a large angle of attack
Yes.  Higher angle of attack.
2. When the aircraft is banked and aft cyclic is applied, the airflow relative to the aircraft is like when it is in a very high rate descend
No. Not the same.
3. The critical angle of attack is exceed on the rotor blades, they stall and cease to produce lift
While technically true, the reduction of Rotor RPM (Nr) is your cue to Stop Doing That! (whatever "that" is) so that Nr does not decay further.  Note that the retreating blade will tend to stall first, which is a different stall mode than a fixed wing aircraft stalling due to high AoA.
4. Due to the greatly increased drag, the main rotor is unable to keep rpm up with its power, therefore rpm decreases
It's the Engines that can't keep the rotors turning that is causing the Nr to droop ...  and that's due to the loads you are putting on the drive system.
5. As rpm decreases, less lift is produced and the stall worsens.
Less lift is produced and you may approach the stall rpm (somewhere around 70-80% of rated Nr depending on the helicopter) if you don't do something to restore Nr.  That means lessen the severity of the maneuver and stop overloading your engines' ability to keep the rotors turning as soon as the Nr droops.
6. By reducing collective, the drag of the blades is reduced, and rotor power is enough to keep rpm at normal range again.
No, the Engine Power is enough (or becomes enough) to keep the Nr in its proper range, but reducing collective is a key first step (as is leveling the wings) to retain control of your rotor system.
Is my explanation correct?
No
Can this happen in real life?
Flying a helicopter like it's an F-18 in a Blue Angels flight demonstration is a good way to kill yourself.

In short:  yes.  Rotors and propeller blades are airfoils and will stall when they reach a critical angle of attack just like fixed wings.
Known in the business as rotor stalls, these can occur during all regimes of flight but can occur in extreme pitch up attitudes, usually encountered during takeoff and landing.  A helicopter's Vne is also calculated as the maximum forward velocity which the helicopter can reach before the retreating rotor blades stall.  Stalls are also common during autorotate even landings when inexperienced students apply hard aft input to the cyclic as they watch the ground rush toward them.
It would be reasonable to expect, therefore, that at high loading near maximum for the airframe and depending on the velocity vector of the air entering the rotor disk that a stall could happen in all or parts of the rotor disk.  You would probably feel buffeting followed by rapid sinking or abrupt rolling or pitching moments at the onset of this.
https://www.aopa.org/news-and-media/all-news/2014/may/08/rotorocraft-rookie-helicopter-stalls

"apply hard aft input to the cyclic " I think you mean pull up on the collective?  Pulling hard is never good but pulling aft cyclic at the bottom of the auto is required to convert speed into rotor RPM.

Please go over your answer again.  I'm afraid that it, and the article you link to, have many problems.  I'll have to down-vote if you can't get it fixed.

The only rotor stall that cab be recovered (ignoring the tail rotor which can stall like any other aerofoil) is a retreating blade stall.  Stalls due to exceeding the critical angle are not recoverable and will lead to a crash.  Stalls are not common in any regime, since they usually result in death and students are therefore trained from the first minute to not do the things which lead to stalls. Extreme pitch attitudes are not attained during take-offs and landings and are certainly not common in autorotations.  The rookie mistake is to pull collective but the instructor will stop the stall.

The article you link to confuses lots of different things - see the comments further down the page.  Sorry, but this answer is not correct in any way - most importantly that the answer to the OP question "is the explanation correct" is no.  More detail is needed to answer is if asked as "what would happen" but the likely result is that rotor would stall resulting in a crash or a blade would strike the tail or cockpit, resulting in a crash.

Carlo, are you referring to powered or unpowered flight?

I will answer the question as written, but as I stated in a comment, it would be better posed as "what would happen if..."
The answer is "no" and "no".

In the game, if the player banks the helicopter then make a sudden and
  hard pull on the cyclic to make a turn while max collective is
  applied, the low rpm warning will sound, followed by a loss of power
  and a few seconds later loss of attitude control.

This is wrong.  Therefore the recovery is wrong.  Therefore your explanation is wrong.  Therefore it could not happen in real life.
If you were to bank an AH6, then pull full collective, then pull back hard on the cyclic, you would die (assuming you are high enough to not survive the crash).
Without spending time thinking through all of the interactions, and since that is not the question asked I haven't done so, either the rotor will stall, which is not recoverable, and/or a blade will strike the tail or the top of the cockpit, which is also not recoverable.  I suspect a rotor stall would occur first, which depending on a lot of factors might then result in a fuselage strike but one or the other will happen almost immediately.

While "no" may technically answer the question, I think an explanation of why the explanation is wrong and/or more detail on what would happen to a real helicopter would be good to include. Unless you think it really needs (or already has?) its own question.

In my opinion, it needs it's own question.  The portion I've highlighted, from which the rest of the question follows, will result in a crash.  I'm not sure what else to say!


text:
Supersonic Fuselage design
What should be the ratio of the fuselage and wings in a maximum dimension limited condition supersonic delta wing aircraft?
Also can anybody explain clearly the "supersonic area rule" or "Whitcomb area rule"?
Is there anything else I need to take care of while designing a fuselage for supersonic conditions?
Thanks.

you could start by taking some lessons in aerodynamics and fluid dynamics.

Way above my pay grade, but a short answer is that if you plot the length of the aircraft on the x-axis and its cross sectional area on the y-axis, you want that curve to be as smooth as possible. If it isn't, you're going to have a large drag rise during transonic flight. So, if, say, as was true with the first F-102, you got a sudden increase in cross sectional area at the point of the fuselage and wing juncture, you could fix it (and they did) by narrowing the fuselage at the point to produce the now familiar "coke bottle" shape, which avoided that large drag rise.

Gaurang, you seriously cannot expect to rock up to some internet forum and find out everything you need to know to design supersonic planes. Very probably, nobody here has that kind of knowledge. Even if they did, it's the sort of thing you'd need to write a whole book to explain, if not a series of books. Nobody is going to invest that kind of time.

@DavidRicherby Also, this is not a forum.

A continuation of my previous comment: As I remember it, the area rule was necessary in an era of engines with insufficient power to overcome the transonic drag rise without it and then push aircraft through the transonic range. It's not necessary and not used today with our much more powerful engines.

@Terry: Wikipedia says the area rule is still important today, citing examples such as the A380 and Citation X.

There is no ideal ratio. Make the wing as big as it needs to be for your take-off run, your cruising altitude or your approach speed, whatever demands the biggest wing, and make the fuselage just big enough to hold the pilot(s) and all equipment, payload, fuel and whatever you choose to carry around. Asking for a specific ratio without any details on the mission or the design parameters is silly.

The comments tell me I should say something about area ruling, though. Terry correctly mentions the x-wise gradient of the aircraft's cross section, but this is only helpful at Mach 1. At higher speeds, you need to look at the area which is covered by Mach cones which run along the longitudinal axis. Sum up the area of the intersection between those Mach cones and your aircraft's structure, and make the lengthwise distribution follow a Sears-Haack-body. Please note that the inclination of those Mach cones varies with angle of attack, so there is not a single optimum shape, but only a best compromise for all expected flight conditions.
Area ruling is only helpful around Mach 1, but there (or slightly above) is the transsonic drag maximum, and area ruling helps to get across this quickly, even with the high thrust of modern engines. If your task is to get to this strange radar blip at 16 km altitude in a hurry, every second counts. Also, modern airliners need to employ area ruling techniques to make cruise Mach numbers above Mach 0.8 economical.
And this is just scratching the surface ...

Am sorry for the question.Should have broken it into multiple specific questions.Thanks for the answers though.


text:
How to plot the pressure distribution over an airfoil?
I have found only the description of this pattern with experimental graphs.Could anyone please tell me the mathematical formula required to plot the distribution?

I'm a little unclear by what you the task. Do you think that you could perhaps include a pictures/figures of what you have got and what you're trying to get?

Funny - answers are pouring in, and we have yet no idea how the pattern looks like.

I have found only the description of this pattern with experimental graphs.

That's because that is the best way to have detailed and precise data: you either simulate (e.g., with Nastran-Patran or XFoil, as cited by Peter Kämpf in his answer) or build a [scale] model and use a wind tunnel. If you use a scale model, depending on the focus of the experiment, you will have to be careful (while scaling back up) not to damage your data: for this you have adymensional quantities to look after, such as the Reynolds number.

Could anyone please tell me the mathematical formula required to plot the distribution?

There is not one formula to do that, but rather a method that given the airfoil shape (and the angle of attack) will estimate the pressure distribution. This method was extensively used in the days before computers and FEM tools existed (for what I know SR71 is a notable example where this method has been used in the early phase of the wings design), but, for what I know, nowadays is seldom used.
The method is based on Conformal Mapping, in particular the Joukowsky transform or the Kármán–Trefftz for more detailed and general cases (see Sec. 4.2 of this pdf for a more in-depth explanation). This is a transformation in the complex plane that, from the airfoil profile that you want to analyse, will map it onto a circle.
You want to do this because the ideal flow around a circle is well known:

At this point you have to know that around an airfoil the air will have a certain amount of circulation and that the total flow around it is the sum of the ideal unviscous flow plus the flow induced by the circulation:

 Image from MIT
For this reason, you want to compute the ideal flow around a cilinder that has a rotation speed equivalent to the circulation around your airfoil[*]:

and it turns out that we have some formulas for that (image above taken from this page).

[*]: note that you will have different circulations for different angles of attack.

Now, why did we do all this? Because once we have the flow around the rotating cilinder and
we have the mapping from the airfoil to the cylinder, we "only" have to invert the mapping:

and we immediately have our flow around the airfoil.
And once we have the airflow, finding the pressure distribution is quite straightforward, thanks to Bernoulli (you have the velocity distribution and you can assume that the transit of the air around the wing is fast enough to be adiabatic)

Conformal mapping is the most simple way to arrive at an exact solution for the inviscid case. Joukowsky airfoils have a circular camber distribution, and the transformation becomes extremely complex when a specific airfoil is to be mapped.

XFoil uses two ways of plotting pressure distributions, one with the chord coordinate on the X axis and the negative pressure coefficient $c_p$ on the Y axis, like that:

The dashed line is for inviscid flow (from the potential flow solver), the solid line for pressure with boundary layer effects.
Another version plots the pressure as arrows orthogonally on the contour of the airfoil, like that:

Please note that negative values of $c_p$ produce arrows pointing away from the airfoil, and positive values point towards the airfoil. In all cases, the formula for $c_p$ is $$c_p = \frac{p - p_{\infty}}{q_{\infty}}$$
$p$ is the local pressure, $p_{\infty}$ is the pressure far away from the airfoil, and $q_{\infty}$ is the dynamic pressure far away from the airfoil.


text:
Are converted airliners fitted with key-operated locks/switches for security?
Light aircraft are commonly fitted with key-operated doors (cabin, cargo compartments) and key-operated switches (magneto/starter) in a manner very similar to most road vehicles. Airliners are not fitted with any such key-operated door latches or essential switches. The difference is due to the security environments in which they are operated/stored. A light aircraft such as a Cessna 172 might be parked in an unmonitored location readily accessible to almost anyone. Airliners are practically never left unattended and unmonitored. But what happens when an airliner is sold out of commercial service and refitted as a private jet? Would such an aircraft still be attended or monitored full time? Do they get fitted with security devices such as key locks on the doors and/or some sort of key operated interlock to deter unauthorized entry or engine starts?

Does this answer your question? Do large commercial aircraft have keys?

@RonBeyer I don't think this is a duplicate. The OP seems to already know about the fact that airliners don't have keys. The question is specifically about the conversion to a private jet.

@RonBeyer I already know about security approaches for airliners used in commercial service. My question is about aircraft converted from commercial to private use and whether this puts them in a security environment more like that of privately owned light aircraft and are therefore fitted with similar security devices (keys) as part of the conversion.

Voting to close as opinion based.  Implementing security measures would be the sole responsibility of the new owner, and there is no concise answer that might accurately capture any and all location factors, and/or decisions that might be made.


text:
What radio frequency bands are associated with the long wire antennas, why do some aircraft have them and others don't?
On many older aircraft, and in vintage aircraft photos, you can often see long wire antennas strung from some point on the top of the fuselage to the top front of the vertical fin. On newer aircraft, it's either a rare find or not seen at all. The fact that some aircraft even today still have them leads me to wonder about their function - which radio frequency bands they are used for, whether those bands are no longer used, or whether the frequencies are still in use but the long wire has been superseded for most installations by a more compact antenna design.
Knowing that modern aviation radio operates in the 108-137 MHz band, and that most modern aircraft use much shorter rigid antennas, the long wire would seem to be inappropriate or unnecessary for that purpose. So, why would aircraft of a more modern design still be equipped with one? What other radio communication (presumably much lower frequency) would call for such an antenna?

They were probably High Frequency band radios, which many aircraft use for long-distance communication. HF radios have wavelengths between 20-160 meters, so antennas have to be physically bigger in most cases

VHF (today's band) requires ground stations at visual range. In the past, stations were very few, an aircraft was most of the time out of sight of any station. The range had to be larger, and HF was used because HF signal can travel on long distances. HF antennas were long wires. Crossing oceans still require HF and SELCAL if SatCom is not used. Antenna is located in the leading edge of the vertical stabilizer. GPS has replaced LORAN.

@mins I don't think SELCAL is actually required... it just makes things much nicer for the pilots, not having to listen to HF static for hours on end.  But AFAIK it isn't required to dispatch overwater, and many USAF aircraft that cross "the pond" don't even have it installed.

@RalphJ: Correct, SELCAL is not required, and if the aircraft is fitted, an inoperative equipment doesn't prevent from taking off. Thanks for correcting. (I read on PPRuNe that Swanwick Oceanic has no SELCAL at all.)

Depending on the aircraft you could be looking at one of a few things.

(source)
On some older aircraft it may be the communications antenna for older style radios (pre UHF/VHF days). Most of these radios have been phased out for some time but you will see it in pictures.
The more common thing you are seeing (based on your top of the fuselage to front of the tail description), as it is still in place on many small GA planes and any bigger planes that have not had the unit removed is the ADF Sense antenna. This antenna helps to deal with the directional ambiguity problem in an ADF unit. Basically the loop antenna is capable of knowing where the station is but only on a 0-180 degree plane. It does not know if it is in front or behind the antenna. The sense antenna allows it to solve this ambiguity. These units operate in the 190-535kHz range. For what its worth the FAA is pulling a lot of ADF's and their associated approaches as GPS takes over but they seem to still be common elsewhere in the world.
Here is one,

(source)

Why do some aircraft have them and others don't?

Since it seems like we have settled on the ADF sense antenna as the one in question it boils down to weather or not your airplane has an operational ADF installed. ADF's are still popular elsewhere in the world but here in the US much of the ADF system is being pulled as it was in part replaced by the VOR system much of which is to an extent being supplanted by GPS today. Since a large chunk of the GA fleet and to an extent the commercial fleet has airframes dating from the ADF days many of the planes still have the systems installed. Depending on where you are located, if you routinely fly one of the remaining ADF approaches or otherwise use an ADF regularly you may elect to keep it in your aircraft. I can tell you that none of the aircraft I trained in had operational ADF units although two of them had units with antennas but were non operational and simply had yet to be removed.

OK, I think the observation behind my question was related to the ADF sense antenna. For a time, my father owned a light aircraft which was equipped with an ADF but had no such sense antenna. IIRC, it was vulnerable to the sense ambiguity problem - you could derive a course between aircraft and transmitter, but could not be sure if it was to or from, so had to use some other means to resolve it, such as another station.

I second @Dave's conclusion that they are ADF sense antenna’s. They removed a long-wire antenna from mine when I had the ADF removed.

It's also possible if the ADF system was installed in the last 30 years that they installed a combined loop and sense antenna.  They are electrically tuned and have to be matched to the receiver, but they are about the size of a small notebook (20 cm wide x 30 cm long x 3 cm high).  A fair number were changed out in the 80's when old units died.  Getting rid of the long-wire gets rid of a lot of drag.

So why does it have to be in the form of a wire? The 787 has the HF antenna as a normal antenna?

The "long wire" antenna is an HF antenna, and operates in the 2 to 30 Mhz band.
Not all aircraft will use them, only aircraft that need to communicate further than a VHF radio. Typically these are found on larger aircraft including some larger helicopters.
The Sea King helicopter uses this antenna as well.
It is still appropriate today as the propagation with the electro magnetic waves in this frequency band is much higher than the VHF band and allows for the aircraft to communicate part way around the world.

The HF bands are for transoceanic communication whereas VHF/UHF coms are used over land and are generally line of sight, At 37K ft Line of sight is approx 300 miles With HF communications are affected by daytime atmospheric signal absorption. Anything about 10MHz or above during daytime, below 10MHz during nighttime


text:
Do regulations permit an airliner be equipped with a radio transmitter which cannot be controlled by the crew?
In response to the case of MH370, an idea which has been floated is that of a device to transmit an aircraft's GPS position. Not specified is whether such a device would be operable by the flight crew.
Among the scenarios suggested to account for the aircraft "going dark" and its apparent flight path is intentional action by someone aboard.
To provide aircraft position (or any other parameter) reporting free of any possible interference by anyone aboard the aircraft would require installation of equipment inoperable by and therefore in a location inaccessible to anyone (crew included) during flight. That means such equipment could never be powered down while the aircraft is in flight.
Have there been/are there currently any regulations which would prohibit the installation of such a device for any reason - e.g. fire safety, possible interference with other radio equipment essential to safe flight (navigation, communication)?

All equipment on board needs to be interruptable, either by direct control input (turning it off) or via circuit breaker. This especially holds true for equipment that is capable of broadcasting or emitting radio waves, such as radio telephony equipment or the transponder.
If the transponder for any reason became damaged and started to send incorrect replies to ground interrogation, it needs to be shut off in order to not confuse ATC systems or other aircraft's TCAS. Electronic or electric systems also need to be shut down in case of eletrical fires or other safety hazards to the aircraft.

To my knowledge, there hasn't been any regulations, but airlines are still using the manual transponder because of the current SOPs.
It is part of all airlines' SOP to toggle the transponder to STBY while at the gate and departing. One of the reasons is to reduce the amount of radio waves present. Other reasons include the display of departing aircrafts while at the gate. Usually, it would be switched to TA/RA during the Before Takeoff Checklist (Airline SOPs vary. I don't speak for all).
So to answer your question, there's no regulations that I know of, so it's more of the airlines' choice. When I had a conversation with a long haul pilot, he mentioned that a couple of times the transponder would be left on TA/RA while at the gate, which means yes, it's do-able, but will airlines adapt to it, probably not at the moment. In the future, perhaps.
Hope that answers your question, or at least helped a bit.

See http://aviation.stackexchange.com/a/11651/753 for regulations.


text:
Why are there GPS MOCAs?
The Pilot Controller Glossary (and other places) define MOCAs as:

MINIMUM OBSTRUCTION CLEARANCE ALTITUDE (MOCA)− The lowest published
  altitude in effect between radio fixes on VOR airways, off-airway
  routes, or route segments which meets obstacle clearance requirements
  for the entire route segment and which assures acceptable navigational
  signal coverage only within 25 statute (22 nautical) miles of a VOR.

VORs aren’t used in GPS navigation so I don’t understand why there would be a GPS MOCA on a T-Route or Victor Airway.
Even the example given in the Aeronautical Chart Users Guide (p56) has a GPS MOCA below the MEA.

Here’s a segment of a Victor Airway in Florida with a MOCA of 1300 but the MEA for GPS is 3000.

I would think the GPS MEA would be the MOCA or even lower, since VOR reception isn’t required in the first 22 miles. If you fly at the MEA it guarantees that a normal climb will keep you above obstacles when entering the next segment with a higher MEA. But I would think that the MOCA would do the same thing unless there was an MCA. So that doesn’t seem to be a reason.
There are even T-Routes in Florida with a GPS altitude and a lower GPS MOCA. That makes even less sense to me.
Does the GPS MOCA also take into account communication reception—but in that case why isn’t that mentioned in the regular MOCA definition?
If anyone could shed some light on how they come up the GPS MOCAs it would be appreciated.

As far as I know, the only thing an MEA provides that a MOCA doesn’t is navigation reception past 22 NM. If it provides more than that, I’d be interested in knowing what else.

It seems to me that you are asking the wrong question. MOCAs, as you note, are determined by obstacle clearance requirements. MEAs also provide this clearance, as well as meeting additional requirements, such as airspace and communication requirements (especially for RNAV routes). Shouldn't your question be more along the lines of, "how are MEAs determined?".

@JonathanWalters As you noted, I’m confused. Why does the MOCA differ from a GPS MEA if the only thing different is the navigation signal. Maybe there are other things that determine the MOCA other than navigation signal coverage?

likely though I don't know for sure that the GPS portion of that document was before SA was disabled and GPS was not considered an accurate height vs position while SA was in play. the higher altitude would have been needed for additional safety margin.

MOCAs provide minimum obstacle clearance, as you note; MEAs also provide this—and more.
MOCAs are determined essentially the same across the board. The question that I think you should ask is why is the MEA higher than the MOCA in some cases where you might not expect it, namely in the case of some GNSS MEAs.
Firstly, all MEAs take into account multiple factors, including those described in the following. Note the mention of airspace buffers and communications requirements.
From the FAA's Instrument Procedures Handbook, on p. 2-35:

The MEA is the lowest published altitude between radio
  fixes that assures acceptable navigational signal coverage
  and meets obstacle clearance requirements between those
  fixes. The MEA prescribed for a Federal airway or segment,
  RNAV low or high route, or other direct route applies to the
  entire width of the airway, segment, or route between the
  radio fixes defining the airway, segment, or route. MEAs
  for routes wholly contained within controlled airspace
  normally provide a buffer above the floor of controlled
  airspace consisting of at least 300 feet within transition
  areas and 500 feet within control areas. MEAs are established
  based upon obstacle clearance over terrain and manmade
  objects, adequacy of navigation facility performance, and
  communications requirements.

Earlier, on p. 2-16, the requirement for communications reception in the case of GNSS MEAs (at least those on RNAV T-routes) is explicitly stated. This makes sense given that these two factors are the primary factors needed in flight guided by GNSS.

A GNSS MEA for each segment is established to ensure obstacle
  clearance and communications reception.

I'm not sure that this answers your stated questions, but I do think it should ultimately answer what you are wondering.


text:
Where can I find the NTSB order for Administrator v. Walkup and/or v. Hamre?
In a footnote to Administrator v Strobel, the NTSB states:

Our precedent makes clear that, “[r]egardless of who is manipulating
  the controls of the aircraft during an instructional flight, or what
  degree of proficiency the student has attained, the flight
  instructor is always deemed to be the pilot-in-command.”
  Administrator v. Hamre, 3 NTSB 28, 31 (1977). This principle was
  reaffirmed in Administrator v. Walkup, 6 NTSB 36 (1988).

THE PILOT IN COMMAND AND THE FARS: THE BUCK STOPS HERE (ALMOST ALWAYS) has some other examples of determining who is PIC and also refers to Hamre.
I can’t find either one on the NTSB site or with a search. Does anyone have a copy or a link to Hamre or Walkup?

@mins It might be helpful if you explain (answer or comment) how you found the Hamre order, that looks like the main question.

@mins I found Hamre and Moeslein but can’t find Walkup with your link. If I try to go directly to the NTSB site that you are searching, I need a login ID and password. Is there somewhere on the site where you can get one?

@mins Another question. Hamre is referenced as 3 NTSB 28, 31 (1977) but the order number is EA-4232. How do you find the order number from the reference?

Here is the opinion and order from Hamre.

@JScarry here are some excerpts from Walkup, I'm looking for the entire case because I too am interested.  http://justhelicopters.com/Portals/5/NTForums_Attach/walkup%20decision.pdf


text:
If I have multi-engine land, can I learn multi-engine sea directly?
Let's say I hold PPL privileges for Multi-Engine Land. Now I want to start my seaplane training.
Can I begin my training directly on a multi-engine seaplane? Or, do I have to get a license for Single-Engine Sea first before I can proceed to multi-engine?

For what it's worth, you can actually start training (as a student pilot) in a multi-engine land airplane if you wanted to.  Not really recommended, but it would be legal!

As shown on page 77 of this FAA document, the various tests needed for an AMES (air multi engine sea) rating depend on the ratings you already hold and your area of operation. Depending on your area of operation, holding an AMEL (air multi engine land) rating can allow you to skip most or all of the required tasks for an AMES rating. In many cases, an AMEL rating is actually better for getting an AMES rating than a single engine sea (ASES) rating will be. So in short, you do not need an ASES rating first, but having one can make the process of getting an AMES rating easier in certain areas of operation.


text:
Does a military equivalent to civil ATC exist?
There are specific military ATC facilities, e.g. at military airfields, or temporary airstrips:

Mobile ATC towers used by US Air National Guard’s for access to hurricane-devastated areas. Source: AAR
But is there usually an overall specific military ATC system for training and/or war operations so that:

Military aircraft / formations are kept separated.
Drones and aircraft don't collide.
Military traffic is well-ordered over large areas.

The scope for answers could be NATO or other large military organization worldwide.

Yes, for their airspace.
Generally speaking, US Military has its own ATC for domestic military installations and other venues such as US Navy aircraft carriers. Most of these military-staffed airports are rarely transited by civilian aircraft, and are instead designed to let the military run their own show with their own aircraft.
At some airports around the country which provide provide joint military-civilian use, such as Charleston Air Force Base in South Carolina, Scott Air Force Base in Illinois, and Marine Corps Air Station Yuma in Arizona. These airports have significant military traffic and also allow civilian aviation operations. At such airports, typically FAA controllers are in place and military aircraft work with them.
Most of the airspace in the US is owned by Air Route Traffic Control Centers, which are staffed exclusively by FAA-employed civilian controllers. These controllers handle all air traffic between airports, including military aircraft transiting the national airspace system, which means that civilian and military facilities all around the country must interact with each other on a daily basis. As a result, both civilian and military air traffic controllers use a commonly shared phraseology.
For exclusive military use, there is special use airspace which includes:

... restricted airspace, prohibited airspace, military operations
  areas (MOA), warning areas, alert areas, temporary flight restriction
  (TFR), national security areas, and controlled firing areas, typically
  up to FL180 or 18,000 ft above sea level.

Source
As discussed in this question, supersonic operations in the US are also performed in airspace which belongs exclusively to military.

In some of the joint use areas, the ATC services are provided by military controllers to both military and civil users. In the vicinity of Eglin AFB, ATC is under the command of the 96th Operations Support Squadron. Fly into Destin (KDTS) and you'll need to talk to Eglin Approach.

As Farhan says, peacetime (or non-combat-zone) military traffic may be controlled by civil or military ATC using the same or similar rules as for civil traffic. Military flights might operate in formation (standard or nonstandard) just as civil flights might. Military flights might also operate under Military Assumes Responsibility for Separation of Aircraft (MARSA) rules, meaning two planes that are not a "formation" flight will get closer than usually allowed (for example during aerial refueling or simulated dogfighting), and the military takes responsibility for ensuring they don't crash by training the pilots properly. Special-Use Airspace is set aside for military flights, and MARSA applies to all military aircraft operating within the SUA.
But you asked about combat operations. Generally combatant aircraft will be controlled by "standard" ATC until they get near to the combat zone, where control will be transferred to a dedicated military Command and Control unit such as the USAF's KINGPIN (article 1, article 2) in Afghanistan. Combat-zone ATC may also be provided by individual Combat Controllers who are more similar to infantry soldiers than to radar controllers sitting in a dark room away from the battle.

Welcome! Interesting information.


text:
Are all tires on an aircraft replaced at the same time?
On cars, it is often to replace all four tires at the same time. Is this true also for aircraft?
I imagine the nose gear and main gear probably can be replaced at different intervals. However, are tires within the same gear assembly replaced together? What about left and right gears? For example, is it ok to replace all tires on the left gear only while keeping old tires on the right?

'On cars, it is often to replace all four tires at the same time. ' I think this is a false assumption. Most people replace one tyre at a time, or maybe an axle (Front or back) at a time. There's no need to replace all 4 tyres on a car. For light aircraft it's definitely the same (Replace as required)

@Dan in several (maybe many) countries it's required by law to replace all tyres on the same axle together (except in emergencies of course, like putting on a spare when you have a puncture). This to prevent control problems due to uneven wear.

@Dan I've never not replaced all four tires at the same time, and know of nobody who suggests that. With proper rotation, all four will reach end of life at the same time. Plus you must have tires matched on the drive axle or wear to the differential will result, so if you're replacing one at a time, they become mismatched. (On an AWD/4WD, you'll damage the transfer if all 4 aren't matched). In fact, this observation answers the question: there's no drive axle and differential on an airplane, so there is no need to match tires precisely.

@user71659 Here in the UK I'd say it's fairly rare to change all tyres at once. Truth is, most people don't rotate and punctures and minor tracking issues will generally dictate that odd tyres get replaced. You won't damage you're average 2WD car by a minor mismatch of tread depth, though of course you should always have 2 similar tyres on an axle

Airline tires are replaced on-condition and are generally recapped until the tire carcass condition deteriorates or is damaged to the point recapping is no longer viable.  There is no regulatory limit, at least in North America, on the number of times a tire can be recapped if the carcass is serviceable.

Nope.. they are replaced 'on condition'. Exception is when one tyre has deflated before landing (cockpit indication and later confirmed) then the good tyre on the same axle has to be replaced irrespective of condition.
Tyres have a hard life and get damaged by rubbish on the runway and stand. Also airplanes don't always hit the ground straight .. when they come in at an angle  it wears the side of the thread more on that tyre.

True for the US (the only country I have experience) however  jwenting implies this is not the case for all countries - though they failed to qualify that statement.

@jwzumwalt jwenting's comment was about cars. For them, common sense (and sometimes laws) require to replace tyres on the whole axle. For aircraft, the situation is very different.

On small planes, tires & inner tubes are used, not like cars which use tubeless tires.
Tires are also different sizes & plys. For example, my POH (Pilot Operating Handbook) calls for 4 ply 5"x5 nose wheel and 6 ply 6"x6 main gear.  I recently had a pinhole wear thru on a main gear tire, so it went flat after 2-3 days, requiring a tube change. The tire itself was fine.
So changing the parts that are worn is the norm.


text:
Can single engine planes glide from a falling position?
Near the end of the 50s Sci-Fi movie This Island Earth, the protagonist is escaping from a flying saucer which is crashing to Earth. As he was abducted while flying a plane (specifically a Stinson 108-1), it's sitting in the cargo hold on top of a retracting hatch:

The protagonists then start up the propeller, and once it gets up to speed, the entire hatch seems to disappear and they're dropped vertically out of the bottom of the flying saucer:

They then manage to continue moving straight without going into any kind of dive, before banking out of the shot.
Is this even remotely possible? I would have assumed that when they leave the system of the flying saucer, they will lose the speed which the saucer has and will basically be falling in a stationary position as they have no lift due to the air only hitting the bottom of the wings.

Hope this question is okay, nobody has filled in the on-topic page so I wasn't sure.

We've never really had a problem with on-topic/off-topic. Sure there have been questions closed due to being off topic, but they've, for the most part, been fairly obvious. Whether something is history or religion can be a crap-shoot, however if you're discussing things flying, it's probably on topic here. :)

"I would have assumed that when they leave the system of the flying saucer, they will lose the speed which the saucer has" - I don't understand - you're assuming that the plane will lose all horizontal velocity instantly on leaving the UFO? why would it do that? Maybe I've misunderstood.

It's remotely possible, assuming you can find a suitable UFO :-) If you drop an object from an aircraft it starts falling with the same airspeed that the aircraft has, until drag or other factors slow it down. If you've ever seen a flour bombing competition (or just watched some WW2 movies or documentaries) you may have noticed that you drop bombs before you reach the target, not when you arrive directly over it.
So if the UFO is moving forward at an airspeed greater than the Stinson's stalling airspeed (65mph) - let's say 80mph - then the Stinson will fall into the air at an airspeed high enough to generate lift immediately and it will fly. If you already have the engine running and throttle up as soon as you fall out of the UFO, you will generate thrust and maintain the flight.
In reality - if there is such a thing when a UFO is involved - the Stinson is almost certain to lose some altitude and the wake turbulence from the much larger UFO will have a significant (and potentially very dangerous) effect if the Stinson can't stay ahead of it.

By 'ahead of target', I assume you mean prior to reaching your target (not forward of)?

@tmptplayer Yes, exactly

@tmptplayer I modified the wording to clarify that

Of course, if the UFO's airspeed is greater than the Vne of the Stinson (probably 150mph or so), the Stinson would probably be ripped apart.

Been there, done that. USS Akron and USS Macon

The airship would build up speed to somewhere around 40 miles per hour,    which was just about the stall speed of the F9C-2, and the Sparrowhawk would slowly and carefully maneuver into a position that allowed them to hook up to the same bar that hoisted them out.  Once hooked, the aircraft was hoisted inside of the airship, into its hanger [sic] bay, where a total of four aircraft could be stowed, with one ready to go on the hook/bar, for a total of 5 aircraft. -farmboyzimsflightsims.com

Having the momentum of the carrier ship, dropping into a 40+ mph head wind means you immediately gain lift and are essentially already 'flying'. Dropping from a head-windless stationary object... not so much.

Gah, I didn't see this in Ratchet's answer, but I'll leave it cause I haz pic :)

The sequence you describe are plausible but not without a dive and some turbulence shaking the aircraft as it clears the  wake of the UFO.
The principle it uses is conservation of momentum:
Inside the UFO the aircraft has the same speed as the UFO. If you take away the air (and drag, lift and propulsion) and drop the plane from the hatch; the plane would follow a parabolic arc while the UFO stays right above it supported by sci-fi magic right up until it crashes into the ground.
Now if we add air and assume the UFO is going at cruising speed of the plane then after it clears the turbulent area of the UFO it will have enough airspeed to maintain lift and fly.
Turns out that aircraft have launched from an airship, for example the USS Macon and USS Akron launching sparrowhawks and the 23-class airship was able to launch planes during tests. The launch from the USS Macon involved lowering the aircraft into the airstream below the zeppelin and then letting it go though there there was enough horizontal speed from the airship itself to achieve proper flight after only a short dive.
For a suspended drop from a stationary point the plane needs to be able to pitch down while in a vertical drop while in a horizontal attitude. And then achieve enough airspeed to not stall when leveling out. Most aircraft are designed to point nose down while in free-fall.

I am not sure that a dive is neccessary if there is enough velocity differenttial between the air and the UFO. And talking about UFO´s, those might not produce any wake at all due to all that sci-fi magic technology :D

@yankeekilo but the short drop in still air will be enough to pitch the plane down and give it some vertical speed, also you will want to get away from the thing as fast as possible

Agreed - I was thinking about a moving UFO.

It's quite possible. For videos, look for the X-series tests done by NASA at Edwards AFB. They've been dropping functional, manned aircraft from a B-52 since the late 1940s. Most famous examples are the X-1 (Yaeger's flight breaking the sound barrier) and the X-15. In the videos the dropped aircraft keeps pace with the bomber until they start the engine and rapidly pull ahead.
Early free-flight tests of the Space Shuttle were the other way up - the shuttle was released from the top of a 747 and flew away without incident. Maybe not quite identical as it was already "in flight" at the time.

they have no lift due to the air only hitting the bottom of the wings.

That's where 100% of your lift comes from.

Sure, if the UFO is moving forward at something close to the stall speed of the Stinson then it would drop, have a momentary bump as it goes through the air boundary of the UFO, then fly away. The airplane is dropped in its landed attitude, with the tail on the ground, so the pilot would need to very quickly get the nose down. I would expect Dr Meacham, genius as he is, would think about this ahead of time and be prepared, perhaps having some forward stick applied as the floor disappears.
If the UFO is stationary then it's a bit more complex, but it could still work. The aircraft is dropped with the tail down and no forward speed. The majority of the air flow at first would be from the propeller, which would give the pilot some elevator and rudder authority. If he applied full forward stick right away he might be able to get the nose down quickly enough that the airplane would quickly build up some airspeed and start normal flight. If he wasn't able to get the nose down before the plane drops then it would most likely go into some sort of spin, which would be recoverable.

all planes are designed so that in such situation they go "nose down" on their own. In a fully stalled plane, you could keep your elevator up all the way and the plane will still go nose down.

The other answers given are good, but just wanted to add a few things.  First, the starting velocity of the UFO is the starting velocity of UFO is the starting velocity of the plane.  If the the UFO is going in the +X direction (let's say to the right) at speed v, then if the plane is pointed in the +X direction it will start moving forward at v.  The thrust of the propellers should then propel the aircraft as if it were accelerating from speed v.  If v is above stall speed (as stated above) then it will start in controlled flying regime.  If v is below stall speed, the plane should still have enough control authority (from it's own generated thrust) to pitch down to accelerate to a speed high enough to fly correctly - if the altitude is high enough of course.
But even more fun to think about might be if a modern fifth generation fighter was dropped out.  These fighters have thrust vectoring which in reality could stop the descent and accelerate forward.  The F-22 has a stunt like this in it's airshow routine and it is quite impressive.


text:
What are the printouts/paperwork a captain does at the check-in desk?
While flying American out of Chicago yesterday I noticed that when the captain arrived he went to the check-in desk and first read the monitor of a computer there for a minute or two, then he printed out a one or two page document from a dot matrix printer at the desk. Then for several minutes he made notations on the printout with a pen. Finally, he printed out a much longer document, maybe five or six pages long, folded it up, then went down the jet bridge together with the FO who arrived just as he was finishing up with the printouts.
Can an ATP, ideally an ATP who flies with American, tell me what exactly those two different printouts were and what notations he would have been making on the first one?

My guess is weather report and NOTAMs

@ratchetfreak There is no need to make notations on a weather report. He was not just jotting one thing down. He was writing for several minutes and referring to the screen. Obviously something complicated was going on. I want to hear from a real ATP who actually knows.

The paperwork he was looking at is the dispatch release.  This paperwork will have

Crew names
Fuel information
Filed route of flight
Alternates as needed
Current weather
Forecast weather at destination and alternates
NOTAMS for departure, destination, alternates, navaids and anything along the route of flight.
Deferred MEL items

There are also probably a few things I'm forgetting at the moment.
When the captain gets the release the first thing to do is make sure it is  for you -- correct crew names and airplane.  You'll check the route of flight and make sure it will work (weather) and evaluate the ordered fuel.  You'll review the destination weather, see if an alternate is needed and make sure a suitable one was filed.  You'll also check departure weather and make sure a takeoff alternate is specified if needed.  If the paperwork isn't right, you call your dispatcher, otherwise you sign it and take it down to the airplane.

The one-page item the captain got may have been a pre-departure clearance.  These are generally available via ACARS but can be printed if needed at a terminal.  They could also be other information such as ground delay programs or ground stop information that affects the flight.

Why would he spending 5 minutes writing things down on the paper?

I notice you did not mention a passenger manifest. Is that not generated?

@TylerDurden I had a flow with the paperwork to check off all required items, circle crew names, NOTAMS, etc just to make sure everything was legal and required.  I'd also jot down temp in F and some other notes about it that I'd use in the PA announcement.  He may also have had an amendment or was calculating something based on a PDC if he had one (seeing if fuel worked for the cleared route, etc).

@TylerDurden passenger manifests are for the cabin crew.  The gate agent  prints that for them and gives it to them directly. (at least in my experience)

@casey probably to account for passengers that may not make it onto the plane. You don't want an incorrect manifest.

Is the route als checked by the captain for flying over hostile areas like the Sinai dessert?

@ChristiaanWesterbeek That's either in the NOTAMs or, if it's a company policy, dispatch will have done that already. I don't think it often happens that a pilot disagrees with the route, but if so, he'll have to report back with dispatch. (also, I like your Dutch spelling, but it's really not a 'Sinai nagerecht'...)

What's a takeoff alternate?

@Greg http://aviation.stackexchange.com/q/1195/258

@casey, that's the legal rules of when you need it on the paperwork, but what is it? Is it an alternative in case you have a need to land straight after takeoff (due to say a failure), but the airport you are leaving is below minimums for landing?

@Greg yes, it is so that you know you have a place to land in case you have to air return and your departure field is below minimums to get back in.